Prepare the Berries: Wash all berries thoroughly. Hull the strawberries and chop them into smaller pieces. Mash the raspberries, blueberries, and blackberries lightly with a fork to release some juice.

Cook the Berries: In a large saucepan, combine all berries, sugar, and lemon juice. Stir to combine and let the berries sit for 5-10 minutes to release their juices.

Infuse with Vanilla: If using a vanilla bean, slice it in half lengthwise and scrape the seeds into the saucepan. Add the vanilla pod to the mixture as well. If using vanilla extract, add it after the fruit starts boiling.

Simmer the Jam: Bring the berry mixture to a boil over medium-high heat, stirring occasionally. Once it boils, reduce the heat and let it simmer for 15-20 minutes, until the fruit breaks down and thickens. Optionally, add pectin for a thicker jam and stir well.

Test the Consistency: Place a spoonful of jam on a cold plate and allow it to cool for a minute. Run your finger through the jam; if it wrinkles, it’s ready. If it’s too runny, simmer longer.

Finish the Jam: Remove the saucepan from heat and discard the vanilla pod if used. Stir in salt (optional) to balance sweetness.

Jar the Jam: While the jam is hot, pour it into sterilized glass jars, leaving about ½ inch of space at the top. Seal with lids and allow to cool at room temperature.

Store the Jam: Store the jam in the fridge for up to two weeks. For long-term storage, process the jars using a water bath canning method.